Timbre (e.g., timbre/timbral attributes) is a quality/character of audio, regardless of audio pitch or loudness. Timbre is what makes two different sounds sound different from each other, even when they have the same pitch and loudness. For example, a guitar and a flute playing the same note at the same amplitude sound different because the guitar and the flute have different timbre. Timbre corresponds to a frequency and time envelope of an audio event (e.g., the distribution of energy along time and frequency). The characteristics of audio that correspond to the perception of timbre include spectrum and envelope.
The figures are not to scale. Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts.